Geographic Range

Habitat

Large slit-faced bats are most commonly found in swampy sites in rainforests. They make their roosts in hollow trees, small caverns in rocks, hollow fallen logs, and manmade structures. Large slit-faced bats are also found in dry savannah habitats. (Hickey and Dunlop, 2000)

Physical Description

Large slit-faced bats are large bats that have reddish brown to gray fur on the top part of their body and paler and grayer fur on the underside. A female found in Zambia had a slight yellow tinge around its neck and shoulders. The face has a deep frontal groove that houses the noseleave and extends from the nostrils to a line joining the base of the ears. This groove is surrounded by fleshy lobes and flanges. Large slit-faced bats are not sexually dimorphic in size. Their tails range in length from 65 to 75mm and terminate in a Y or T shaped piece of cartilage. Their body and head length ranges from 63-93 mm and their body mass is from 23 to 36 g, which makes them the largest member of the family Nycteridae. They have large ears, ranging from 28 to 35 mm; this can be as much as 50% of their forearm length. The forearms range from 57 to 66 mm, and their tibias range in length from 29.5 to 33.5 mm. (Fenton, et al., 1987; Hickey and Dunlop, 2000)

Large slit-faced bats have trifid incisors, that is, their incisors are divided into three narrow parts or lobes. A few dimensions of their skulls are as follows: length of skull, 26-27 mm, breadth of zygomatic arch, 16-17 mm, length of maxillary tooth row, 9.1-9.7 mm and width of the maxillary 10.4-11.1 mm. (Fenton, et al., 1987; Hickey and Dunlop, 2000; Parey and Berlin, 1993)

Member of the family Nycteridae can be distinguished from all other bats by their tails ending in a Y or T shaped piece of cartilage. Large slit-faced bats can be distinguished from all other Nycteridae except Nycteris hispida by their trifid upper incisors. They can be distinguished from Nycteris hispida by the larger size and forearm length of N. grandis. Large slit-faced bats have skin temperatures that range from 33.5 to 38.0°C. (Fenton, et al., 1987; Hickey and Dunlop, 2000)

Reproduction

Little is known about the reproductive and mating habits of large slit-faced bats. It is likely that these bats are monogamous because pairing and roost fidelity is quite common in this species. (Fenton, et al., 1987; Park and Myers, 2004)

Little is known about the reproduction and development of large slit-faced bats. One offspring is born to a female per breeding season. It is possible that there are two breeding seasons, but this is uncertain. In one study in Zimbabwe in December, some female large slit-faced bats were found with offspring that were 1-7 days old. In Liberia, a female was found in December with a 5 mm embryo. Another study collected 7 females in September in Zambia; these had single fetuses with crown-rump lengths of 24-27 mm and head lengths of 17-18 mm. The amount of time to weaning and the age at which the offspring reaches sexual maturity is unknown. In related bats such as Nycteris hispida and Nycteris thebaica adult size is reached in about two months, and females continue to nurse their offspring from 45 to 60 days. (Hickey and Dunlop, 2000; Park and Myers, 2004)

It has been documented that females and their young can recognize each other. In several cases, when a female returned to a roost after foraging, her offspring recognized her and began to rapidly flap its wings. (Hickey and Dunlop, 2000; Park and Myers, 2004)

Lifespan/Longevity

There is no information on the lifespan or longevity of this species. Large slit-faced bats most likely live for many years since most microchiropterans are fairly long lived. (Esmailka and Olson, 2005)

Behavior

Nycteris grandis can be found roosting alone, in pairs, or in small groups. These bats show high levels of roost fidelity; that is, they return to the same roost each day. Large slit-faced bats use a variety of different roosts for day roosts, feeding roosts, and night roosts. Females pass the day and nurse their young in day roosts. Night roosts are used as hunting perches. Nycteris grandis individuals take prey that they have caught to a feeding roost, which is usually within 20 m of their day roost. This may be a strategy to avoid having their prey stolen by other bats in the day roosts. ("Regions Containing Large Slit Faced Bats", 2006; Bayefsky-Anand, 2005; Fenton, et al., 1987; Hickey and Dunlop, 2000; Parey and Berlin, 1993)

Migratory patterns in Nycteris grandis have not been observed, however the related bat Nycteris thebaica has been known to migrate. There is little information about why this occurs in Nycteris thebiaca and it has been hypothesized that migration occurs as a result of resource availability.

Home Range

There is no information about the home range of this species.

Communication and Perception

Like many other bats, Nycteris grandis uses echolocation. During attacks Nycteris grandis produces echolocation calls, increasing the rate of calling as it approaches its prey. The spectra of calls early in the feeding sequence have four peaks (20-112 kHz), and the calls later in the approach have a single peak at approximately 73-91 kHz. The minimum and maximum frequencies of the early calls in the approach are 17 and 114 kHz and for the later calls are 61 and 110 kHz. The pulse duration varies from 0.6 to 2.8 ms and the interpulse interval varies from 6.0 to 17.8 ms. Nycteris grandis emits echolocation calls through their nostrils, and their noseleaf may play a role in ampilyfing the sound. Large slit-faced bats also use other modes of perception to locate and capture prey, including passive hearing and vision. The large ears of Nycteris grandis have their higest sensitivity between 10 and 20 kHz, a frequency used to detect sounds made by prey. ("Regions Containing Large Slit Faced Bats", 2006; Bayefsky-Anand, 2005; Fenton, et al., 1987; Hickey and Dunlop, 2000; Parey and Berlin, 1993)

Interspecific communication has not been widely studied in bats, but it is likely that large slit-faced bats use chemical and auditory cues, as well as tactile and visual cues, to communicate among individuals.

Food Habits

Large slit-faced bats are opportunistic foragers that use two foraging strategies and eats a broad range of prey. Large slit-faced bats eat arthropods, bats, frogs, fish and birds. Their diets vary based on the season, with frogs being the most common prey in March, April, May, August, and September. Other bats are common prey in June and July, and arthropods are most common in December, January, and February. For large prey like bats and birds, Nycteris grandis grasp them in their mouths and immobilize them with a strong bite to the head. (Fenton, et al., 1987; Hickey and Dunlop, 2000; Parey and Berlin, 1993)

Large slit-faced bats use two foraging strategies. The most common strategy involves hunting from a perch where the bats wait for prey to pass by. They then use short flights to attack the prey on the ground where they envelop it with their wings. They also take longer flights in search of food on the ground or in the air. They switch between each type of foraging strategy based on habitat and prey availability. Large slit-faced bats hunt at night from night roosts. They use prey-generated sounds to locate their targets, which explains why noisy prey are their most common targets. ("Regions Containing Large Slit Faced Bats", 2006; Bayefsky-Anand, 2005; Fenton, et al., 1987; Hickey and Dunlop, 2000; Parey and Berlin, 1993)

Predation

Little is known about the predators of Nycteris grandis. The most common predators of bats in the genus Nycteris are snakes and large birds of prey, for example bat hawks. Possibily to avoid predators, these bats roost in high places where it is hard for predators to get to them. (Esmailka and Olson, 2005)

Ecosystem Roles

Nycteris grandis has a large impact on many different species in their ecosystem because they eat such a wide variety of foods. Like many bats, Nycteris grandis eats large amounts of insects which likely affects the populations of those species. They also feed on vertebrates, including other bats. Large slit-faced bats are hosts to parasites called broad trypanosomes, but there is little information available about this relationship. (Hickey and Dunlop, 2000)

Commensal/Parasitic Species

broad trypanosomes

Economic Importance for Humans: Positive

These bats eat insects, helping to control pest populations.

Positive Impacts

controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of Nycteris grandis on humans.

Conservation Status

Large slit-faced bat populations are not currently considered threatened.

Contributors

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

echolocation

The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

suburban

living in residential areas on the outskirts of large cities or towns.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

ultrasound

uses sound above the range of human hearing for either navigation or communication or both

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

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The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

This material is based upon work supported by the
National Science Foundation
Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.